This invention generally relates to material handling robots, and specifically relates to directly driving arm links and end effectors of a robot.
Material handling robots are used in automated manufacturing of integrated circuits, flat panel displays, and other precision-made products. Many of these products require near-sterile handling of extremely fragile and expensive materials, such as semiconductor wafers, during the manufacturing process. In semiconductor manufacturing, raw materials and in-process workpieces must be kept extremely clean; the circuit paths etched on the workpieces are so small (e.g., 0.18-10 microns) that minute particles can contaminate the paths and render the finished circuit inoperative. Therefore, sealed, ultra-clean robots are used to move the materials accurately, gently, and precisely, within a clean room, preventing contamination or damage to the materials which could occur through human contact or handling. However, such robots must not generate particles of metal, leak chemicals, or produce other materials which could contaminate a wafer or other substrate.
Further, robots must move precisely to specific points in space to carry out various manufacturing steps. Because wafers, flat panels, and other substrates are extremely fragile and expensive, all robot movements must be gentle and precise. xe2x80x9cBacklash,xe2x80x9d or play in the mechanical components of the robot, must be minimized to ensure accurate movement and to prevent damage to an object on the robot.
In addition, some manufacturing processes are carried out in a vacuum, or require hazardous chemicals. Robots must be vacuum-compatible, and able to handle materials in vacuum and corrosive environments which are hostile to humans.
Accordingly, there is an acute need in this field for an ultra-clean material handling robot which is reliable, operates with minimum or zero backlash, fully sealed against particle generation, and vacuum-compatible.
In general, in one aspect, the invention is directed to a robot. The robot has a base, a first link connected to the base by a shoulder joint, and a second link connected to the first link by an elbow joint. A shoulder motor drives the shoulder joint, and an elbow motor drives the elbow joint. An upper elbow pulley is coupled to the first link. An end effector pulley coupled to the upper elbow pulley, and a dual-bladed end effector driven by the end effector pulley. The diameter of the upper elbow pulley and the diameter of the end effector pulley are related by a 1:2 ratio.
Features of this aspect include: a first elbow drive pulley driven by the elbow motor; a second elbow drive pulley coupled to the first elbow drive pulley and driven thereby; wherein the first and second elbow drive pulleys have equal diameters; and wherein the second elbow pulley is coupled to the second link; a shoulder motor drives an arm link, wherein the elbow drive pulleys are mounted in the arm link; the elbow drive motor and shoulder motor are concentrically mounted in a housing; a slip-ring assembly for communicating signals from within the housing to the arm link; the slip-ring assembly comprises a static member affixed to the housing and a moving member affixed to the arm link, whereby the arm link may rotate about the housing; each joint is sealed by a fluid seal; and each fluid seal is a ferro-fluid seal.
In another aspect, the invention is directed to a robot with a shoulder motor, a first arm link coupled to the shoulder motor by a shoulder joint, and a second arm link coupled to the first arm link by an elbow joint. The shoulder joint is sealed by a first fluid seal and the elbow joint is sealed by a second fluid seal.
Features of this aspect include an end effector coupled to the second arm link by a wrist joint; the wrist joint is sealed by a third fluid seal; the first and second fluid seals comprise ferro-fluid seals; the arm links comprise seams, and further comprising a static seal joining each seal; a particle filter in a wall of each arm link; and the third fluid seal comprises a ferro-fluid seal.
In another aspect, the invention comprises a robot arm link having a particle filter in a wall of the arm link. Features of this aspect is that the filter is a high-density particle filter; and the arm link further comprises a closed wall joined in a seam, and a static seal in the seam; and the arm link is vacuum compatible.
In another aspect, the invention provides apparatus for communicating an electrical signal through a revolute robot joint, comprising a conductive slip-ring assembly having a static member affixed to a static link of the joint, and having a moving member affixed to a moving link of the joint. Features of this aspect include a first signal cable coupled to the static member and a second signal cable coupled to the moving member, wherein the static member and the moving member are rotatably and conductively coupled.
In another aspect, the invention provides apparatus for communicating an electrical signal through a revolute robot joint, the joint comprising an outer cylinder and an inner cylinder concentrically mounted in the outer cylinder, the apparatus comprising a cable having an inner end in the inner cylinder, a cable body coiled around the inner cylinder within the outer cylinder, and an outer end extending through the outer cylinder.